Sediment depth is given in mbsf. The abundance of chert in the core is a qualitative estimate based on the amount and type of recovered sediment, the drilling time, torque and pump pressure of coring as determined from the drilling log, experience of the drilling crew, and discussions with the drilling crew during coring attempts. Rare (R) generally means the recovery of only a few fragments of chert (< 1%) within a high-recovery calcareous sediment core, or the recovery of a few fragments when other factors indicate the near absence of chert (fast drill time, low torque, low pump pressure). Common (C) shows a higher percentage of chert in the core (1-10%) and (or) high drill time, high and steady torque, and possibly high pump pressure. Abundant (A) generally indicates that at least 10% of a drilled sequence consists of chert, as shown by high chert percentages in the recovered sediment, and high drill time, torque, and pump pressure. A dash indicates the absence of chert.